This nonprovisional application incorporates by reference the subject matter of Appl. No. 2000-310880 filed in Japan on Oct. 11, 2000, on which a priority claim is based under 35 U.S.C. xc2xa7 119(a).
1. Field of the Invention
This invention generally relates to a vehicle side sill structure, and more particularly to a vehicle side sill structure capable of properly deforming in response to vehicle frontal impact, offset impact, and side impact.
2. Description of Related Art
A frame portion of the vehicle is basically formed to have a predetermined rigidity since it receives various kinds of impacts from the outside while running. In particular, the frame portion of the vehicle comprises a portion that allows deformation for absorbing impacts when receiving an overload, and a portion that improves rigidity with a high priority to ensure a passenger space such as a frame portion around a vehicle compartment.
Incidentally, a vehicle body frame portion, forming the side portion of the vehicle body, is comprised of a roof rail disposed in the lower section of the vehicle body; a side sill disposed in the lower section of the vehicle body; a front pillar, a center pillar, and a rear pillar that connect the roof rail and the side sill; and so forth. Each of these members is usually formed to have a closed section to improve the rigidity thereof. Among these members, the side sill in particular receives an overload (compressive load) in the longitudinal direction in a frontal impact or an offset impact, and it is therefore necessary to inhibit the side sill itself from curving and buckling to disperse the load. Further, when the side sill receives an overload along the width of the vehicle in a side impact, it is preferable to control the mode of bending along the width of the vehicle (the mode of bending of the side sill itself).
However, in a conventional side sill structure disclosed in, for example, Japanese Patent Laid-Open Publication No. 6-99851, an inverted T-shaped pipe member is disposed in an inverted T-shaped space to improve the rigidity in an-inverted T shaped connecting portion between a side sill and a center pillar joined to the intermediate section of the side sill and to inhibit the deformation of the connecting portion in a side impact. In another conventional side sill structure disclosed in Japanese Patent Laid-Open Publication No. 64-18784, a pipe member is disposed in a closed space, which is continuously formed along the longitudinal side of a side sill, through a plurality of bulkheads in order to disperse a load when a vehicle receives an overload (compressive load) along the longitudinal side of the side sill.
Therefore, the above-mentioned conventional structure does not enable proper deformation particularly in a side impact although various measures are taken to improve the rigidity.
It is therefore an object of the present invention to provide a vehicle side sill structure capable of deforming particularly in a side impact.
The above object can be accomplished by providing a vehicle side sill structure, in which a side sill portion having a substantially closed section extending in a longitudinal direction of a vehicle body, is provided at a side of the vehicle body, the vehicle side sill structure comprising: a center pillar joined to an intermediate section of the side sill portion and extended upward; a pipe member disposed inside the side sill portion and extended in the longitudinal direction of the vehicle body, at least two fragile portions formed in a side portion of the pipe member across the intermediate section; and a reinforcing member disposed substantially along the side portion of the pipe member to cover the fragile portions, and cooperating with the side portion to form a second closed section.